编程调节Win7/Win8系统音量的一种方法

#include  
#include  
#include 
#include 


//参数:
//	-2 恢复静音
//	-1 静音
//	0~100:音量比例
bool SetVolumeLevel(int level)
{
	HRESULT hr;
	IMMDeviceEnumerator* pDeviceEnumerator=0;
	IMMDevice* pDevice=0;
	IAudioEndpointVolume* pAudioEndpointVolume=0;
	IAudioClient* pAudioClient=0;

	try{
		hr = CoCreateInstance(__uuidof(MMDeviceEnumerator),NULL,CLSCTX_ALL,__uuidof(IMMDeviceEnumerator),(void**)&pDeviceEnumerator);
		if(FAILED(hr)) throw "CoCreateInstance";
		hr = pDeviceEnumerator->GetDefaultAudioEndpoint(eRender,eMultimedia,&pDevice);
		if(FAILED(hr)) throw "GetDefaultAudioEndpoint";
		hr = pDevice->Activate(__uuidof(IAudioEndpointVolume),CLSCTX_ALL,NULL,(void**)&pAudioEndpointVolume);
		if(FAILED(hr)) throw "pDevice->Active";
		hr = pDevice->Activate(__uuidof(IAudioClient),CLSCTX_ALL,NULL,(void**)&pAudioClient);
		if(FAILED(hr)) throw "pDevice->Active";

		if(level==-2){
			hr = pAudioEndpointVolume->SetMute(FALSE,NULL);
			if(FAILED(hr)) throw "SetMute";
		}else if(level==-1){
			hr = pAudioEndpointVolume->SetMute(TRUE,NULL);
			if(FAILED(hr)) throw "SetMute";
		}else{
			if(level<0 || level>100){
				hr = E_INVALIDARG;
				throw "Invalid Arg";
			}

			float fVolume;
			fVolume = level/100.0f;
			hr = pAudioEndpointVolume->SetMasterVolumeLevelScalar(fVolume,&GUID_NULL);
			if(FAILED(hr)) throw "SetMasterVolumeLevelScalar";

			pAudioClient->Release();
			pAudioEndpointVolume->Release();
			pDevice->Release();
			pDeviceEnumerator->Release();
			return true;
		}
	}
	catch(...){
		if(pAudioClient) pAudioClient->Release();
		if(pAudioEndpointVolume) pAudioEndpointVolume->Release();
		if(pDevice) pDevice->Release();
		if(pDeviceEnumerator) pDeviceEnumerator->Release();
		throw;
	}
	return false;
}



int main()
{
	CoInitialize(0);
	try{
		//3秒后静音
		Sleep(3000);
		SetVolumeLevel(-1);
		//3秒后恢复静音
		Sleep(3000);
		SetVolumeLevel(-2);
		//调节音量
		Sleep(3000);
		SetVolumeLevel(10);
		Sleep(3000);
		SetVolumeLevel(30);
		Sleep(3000);
		SetVolumeLevel(20);
	}
	catch(...){
		//错误处理...
	}
	CoUninitialize();
	return 0;
}